Increased biological oxidation and reduced anti-oxidant enzyme activity in pre-eclamptic placentae

Oxidative stress occurs when cellular levels of reactive oxygen species exceed anti-oxidant capabilities and has been implicated in the pathogenesis of pre-eclampsia. In this study we have examined the tissue levels of endogenous anti-oxidant proteins (superoxide dismutase, glutathione peroxidase, thioredoxin reductase and thioredoxin) and the level of lipid and protein oxidation in placental samples from normal and pre-eclamptic pregnancies. Pre-eclamptic tissue homogenates demonstrated significantly increased levels of lipid peroxidation (20.68±7.811μM/mg protein versus 5.33±4.03μM/mg protein, P<0.001) and a trended increase in protein carbonyl concentration (248.1±97.71units/mg protein versus 209.7±82.6units/mg protein) when compared to controls. The levels and activities of the anti-oxidant proteins superoxide dismutase (2.48±0.6U/mg protein versus 2.02±0.51U/mg protein, P<0.02), thioredoxin reductase (19.25±9.81U/mg protein versus 13.02±5.66U/mg protein, P=0.02), thioredoxin (107.00±18.11ng/mg protein versus 91.12±21.18ng/mg protein, P=0.02) and glutathione peroxidase (17.33±6.63mmol/min/mg protein versus 11.50±3.11mmol/min/mg, P<0.02) were all found to be significantly reduced when comparing pre-eclamptic placental tissue homogenates to gestational age-matched control placentae from non-pre-eclamptic pregnancies. The results of this study demonstrate a decreased enzymatic anti-oxidant capacity and increased oxidation in placental tissue from pre-eclamptic women, which may contribute to the pathogenesis of this complex disorder.